87 OMC 175HP Cobra Drive hesitation when wide open

[markwh]

hi first timer in these forums. i have a 87 omc 175hp engine in a 19ft edson boat just bought it, changed , engine oil, bottom end oit, fuel sepparator and belts. cause it was sitting a couple years. it starts and runs great but when i go wide open at about 45mph and 4600-4800rpm it hesitates or sputters, so i cut back a bit and it runs great. any thoughts, do i need the carbs cleaned maybe?

 

[Reinell-BRXL-191]

Re: 87 OMC 175HP Cobra Drive hesitation when wide open

well, I am betting you are out of camshaft at that speed, I would look up your WOT and determine if someone has re-proped the drive or messed with the linkage settings for the carb... because the engine should run up to it's WOT and not have any more stick for more acceleration.. 4800 seems a little on the high side for the year and size... Of course I am assuming a 4.3 liter.. and the WOT on those is around 4200 or so - and if you are getting 45 mph actual on a 19 footer, there is for sure a prop issue allowing you to push up toward 5K in RPM.. you should be a little slower at WOT

 

[cr2k]

Re: 87 OMC 175HP Cobra Drive hesitation when wide open

Sounds like you may have some sediment or corrosion in the carb. Setting for a few years yes I would do the carb. Also you Need to do the impeller. It should be done every other year weather you use the boat or not. See my sig.

 

[JSMoore]

Re: 87 OMC 175HP Cobra Drive hesitation when wide open

I would go with Reinell-BRXL-191. If you're turning 4800, you're WOT RPM is too high. You didn't say, but according to the manual, if you have the 4.3L V6 2BBL GM engine, your WOT RPM should be in the 4200 - 4600 RPM. (4200 - 4800 RPM for the 4BBL version). I always try to match the propeller to the boat so it runs in the lower area of those ranges. Motors last longer when they're not screaming their guts out. Anyway, if you're starting to sputter at 4800 RPM, I'd say you are just running out of motor. Re-prop your boat to keep 'er in the lower end of the range.